(Annual   Savings=A((1/R)-(1/(OverHat[R])))(((((OverBar[T])^Indoor)-((OverBar[T])^Outdoor))(H))/(η^HVAC))(Price)(47)where Price={(((Price^NG)/(10^5))   if   price   has   units   of   $   per   therm((Price^Electrity)/(3,412))   if   price   has  units  of   $   per   kWh) )